There are many known approaches for connecting a circular rigid shaft to an outer machine element having a circular bore. Press fits are commonly used where the shaft diameter is slightly larger than the bore diameter of the machine element and pressure is used to force the machine element onto the shaft. Alternatively shrink fits can be used by heating the machine element to expand the bore diameter, the shaft upon being placed in the bore and, upon cooling of the machine element, the shrink fit is achieved. Such interconnections are not always convenient in the field and are difficult to disengage.
Mechanical couplers employing the user of wedges have been commonly used. An example of this type of mechanical coupler is disclosed in U.S. Pat. No. 2,956,826. The use of wedges or tapered sleeves provide a good frictional binding between a shaft and surrounding machine element; however, the wedges sometimes interlock and prevent easy disengagement of the shaft from the machined element. Scoring of the shaft may also result. Other types of tapered sleeve interconnection are disclosed in U.S. Pat. Nos. 3,957,381 and 4,202,644 and in Canadian Pat. No. 632,967. Other common approaches to interconnecting shafts or the like to surrounding elements are disclosed in U.S. Pat. Nos. 3,986,583, 4,127,741 and Canadian Pat. Nos. 130,683, 378,366 and 934,530.
A coupling using tiltable, eliptical independent discs is disclosed in U.S. Pat. No. 3,866,726. This form of coupling is acceptable when used as a clutch or brake. When the shaft is rotated, the flywheel moves inwardly of the shaft to cause a tilting of the discs and thereby bind the driven flywheel to the outer surrounding member. The discs have enlarged central apertures which provide for this tilting about the driven member so as to engage the surrounding member to be driven. However, such an arrangement would be unacceptable in providing a secure interconnection of drive shaft to bearings and the like, because the enlarged disc apertures would not assure a concentric mounting of a bearing on a shaft.
Another form of connector, which may be used as a clutch, is disclosed in U.S. Pat. No. 2,922,220. A coil spring is used. When the coil has one end turned circumferentially, the coil contracts to effect a binding between a shaft and outer surrounding member. Another approach in using a coil to form an interconnection is disclosed in U.S. Pat. No. 3,888,598. The wire coil is mounted between a shaft and a member to be driven. The coil is supported between the shaft and the outer member by a support having a helical groove, so as to contain and hold the coil in place. By rotating one end of the coil, the coil is expanded as held within the groove to effect a binding between the shaft and the surrounding member.
Elastomeric materials have also been used in providing couplings. An example of this type of coupling is disclosed in U.S. Pat. No. 3,548,714. The elastomeric material is axially squeezed to couple a shaft to surrounding member. By squeezing the elastomeric material, it forces the material radially outwardly to form the connection.
Spieth disclosed in Auslegeschrift No. 19 38 449 a coupling, whereby axial compression of an insert between shaft and bearing provides a connection. The retaining ring, as inserted between the shaft and outer member, requires extensive metal forming and is, therefore, relatively expensive. The retaining ring is axially compressed to cause expansion inwardly and outwardly of the ring to effect a binding between shaft and surrounding element. Such axial squeezing of the retaining ring induces fatigue stresses in the ring because of the flexing needed to connect the shaft to the bearing member. In so compressing the retaining ring, the elastic limits may be exceeded and as a result prevent disassembly of the bearing from the shaft.
The coupling, according to this invention, overcomes a number of the above problems to provide an inexpensive type of coupling which may be readily used in the field and requires a minimum, if any, changes at all to the shaft and surrounding element to be coupled.